View Full Version : help me with this

01-15-2008, 03:33 PM
hi guys
pls. help me with this Q, I couldn't understand it :bored::

Four drugs produce the same therapeutic effect
by the same mechanism, but each has a unique
toxicity. When used at a maximally effective
therapeutic dose, the drug with which of the
following sets of characteristics is most likely to
have the highest incidence of toxicity?

Median Effective dose-------------- Toxic Dose1/ Effective Dose Effective Dose99

(A) 0.5x ---------- 2.8

(B) 1x -------------2.1
(C) 5x------------- 4.0

(D) 33x----------- 3.0

01-15-2008, 05:33 PM
this is a familiar question anyway, my approach in answering this question is based on therapeutic index.
therapeutic index (TI) = Toxic dose 50 (TD50) or Lethal dose 50 (LD50) divided by Effective dose 50 (ED50). among the choices 2.1 has the narrowest therapeutic index which means high incidence of toxicity. just remember, drugs with narrow therapeutic index has high incidence of toxicity like lithium, digoxin, theophylline, aminoglycosides (gentamicin etc). the therapeutic levels of these drug has to be monitored frequently to prevent adverse effects. hope this help.

01-16-2008, 12:17 PM
i was just confused with median effective doses

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